There has been known a process for manufacturing a battery electrode, comprising the steps of mixing active material with a binder, applying the mixture so obtained to a current collector and drying (see Japanese patent application No. 17545/71, C1. 57C2, 1971).
One of the major drawbacks of said process is its limitation in utilizing more efficient methods of applying the active material to the current collector, with the exception of a method for smearing. This is caused by the fact that, when using these methods of applying active materials to a collector, namely milling and pressing, which allow preparation of electrodes with higher capacities per unit weight, a wet mixture of active materials will be squeezed out. In addition to the above problem, when drying an active material of a smeared electrode, warping is unavoidable so that an additional process for milling becomes necessary to straighten said electrode. Drying requires a complete hardening of a binder. As a result, the destruction of the electrode skeleton structure takes place when the binder polymerizes during rolling and drying. The destruction results in the decrease of electrode strength and flexibility. The destruction also disturbs the contact between separate particles of active materials, leading to the decrease of capacity of such electrodes.
The closest prior art dealing with processes for making electrodes of the same purpose has been described in a method for manufacturing a battery electrode, comprising the steps of mixing an active material with a binder, applying a mixture so obtained to the lead, and drying (see French Patent No.2415882, Int. C1. HO1M 4/32, 1979).
It is, however, impossible to use the above method during one main stage (rolling and pressing), to obtain an electrode with predetermined weight characteristics due to an intense creep of the paste. When applying the paste onto a current collector using the said method, additional means (porous bands, cords, etc.) for dehydrating and keeping clear of the paste to operating parts are required, resulting in considerable complication of the manufacturing process.
Moreover, electrodes made by the said method using a tentative binder possess a limited flexibility which narrows the spectrum of applicability of, for example, small-scale cylindrical primary current generator cells due to the cracking of electrodes while coiling.